Hydraulic brake system in motor vehicles are usually operated with vacuum brake boosters. A vacuum pressure required for this purpose is generally provided by internal combustion engines or with vacuum pumps driven on the side of the engine.
In vehicles provided with electromotive or hybrid drives, vacuum is not supplied constantly via a internal combustion engine. In order to make it possible to provide a reliable deceleration of a motor vehicle, vacuum-independent braking systems are used.
For example, a vacuum-dependent brake system can be designed in such a way that braking is no longer initiated with an activation of a brake pedal by the foot of a driver. For this purpose, during the normal operation, which is to say in an operation without a system error, the braking pedal is hydraulically decoupled from the respective brakes. In this case, a pedal feel or a feedback signal is generated by actuating the brake pedal for the driver by means of a pedal simulator, so that the driver is enabled to perform a mechanical-hydraulic operation in order to actuate the brakes only in the case of an error. Such a hydraulic decoupling of the driver from the braking operation offers new technical possibilities, such as possibilities for an adjustment of a zero position of the braking pedal.
Adjusting a pedal position, or of a zero position of a brake pedal can be useful for a number of different reasons. In most cases, the zero position of a brake pedal is adjusted for ergonomic reasons, for example in order to improve the ease of operation and the accessibility of the brake pedal, in particular with motor vehicles in which a high deceleration occurs when the accelerator pedal is released, such as for example with thrust deceleration or with thrust simulation. If the driver steps on the brake pedal during a thrust deceleration, this will generally result in excessive braking because the zero position of the braking pedal and the pedal force at this point do not correspond to the pedal forces and to the ways for using the pedal that are usually employed with this deceleration for moving the pedal to a position that corresponds to deceleration and that would be expected if the braking were carried out only by means of the brake pedal, which is to say without thrust deceleration or thrust simulation.
Mechanical devices that are currently used for adjusting pedals are very complex, delicate and expensive.
In the German document DE 103 34 191 A1 is disclosed an adjustable pedal arrangement that is provided with a translational adjustment capability and with a rotary adjustment capability.
The German document 10 2013 224 313 A1 discloses a vacuum-independent braking system for a motor vehicle.